The ad said 24 to 30 chickens. It is 20 sq ft. The usual recommendation on here is 4 sq ft per bird in the coop for large fowl, a little less for bantams, so 5 LF in there. Some more experienced chicken keepers recommend more. Your climate should be mild enough that they well be out all day, and you might be able to keep calm, happy birds in 3 sq ft per LF, perhaps even a little less. But if you want 24 to 30 chickens, you will have problems in this coop.
This overestimating of numbers is a common finding among chicken coop sellers. It sounds like a good coop, but not for 30 chickens.